Engine ventilation system diagnostics using pressure measurement

ABSTRACT

A system comprising an engine including a chamber; an air intake coupled to the engine; a pressure sensor disposed in fluid communication with the air intake and disposed between the air intake and the chamber; and a processor configured to determine a breach in a ventilation system of the chamber in response to the pressure sensor.

BACKGROUND

The technical field generally relates to engine ventilation systemdiagnostics and, in particular, to pressure measurements used in engineventilation system diagnostics.

Internal combustion engines can include ventilation systems designed todirect combustion gasses that have leaked past seals, rings, or thelike. The gasses can be directed by the ventilation system into theengine. However, a breach in the ventilation system can release thegasses into the atmosphere.

Therefore, further technological developments are desirable in thisarea.

SUMMARY

One embodiment is a unique system comprising an engine including achamber; an air intake coupled to the engine; a pressure sensor disposedin fluid communication with the air intake and disposed between the airintake and the chamber; and a processor configured to determine a breachin a ventilation system of the chamber in response to the pressuresensor.

Other embodiments include unique methods, systems, and apparatus todiagnose an engine ventilation system using a pressure measurement.Further embodiments, forms, objects, features, advantages, aspects, andbenefits shall become apparent from the following description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a vehicle according to an embodiment.

FIG. 2 is a diagram of an engine system with a ventilation systemaccording to an embodiment.

FIG. 3 is a diagram of a ventilation system according to an embodiment.

FIG. 4 is a diagram of a connection between a pressure sensor and an airintake according to an embodiment.

FIG. 5 is a graph of pressure versus load according to an embodiment.

FIG. 6 is a diagram of a ventilation system according to anotherembodiment.

FIG. 7 is a flowchart of a diagnostic technique according to anembodiment.

FIG. 8 is a flowchart of a diagnostic technique according to anotherembodiment.

FIG. 9 is a flowchart of a diagnostic technique according to anotherembodiment.

FIG. 10 is a flowchart of a diagnostic technique according to anotherembodiment.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated herein.

FIG. 1 is a diagram of a vehicle according to an embodiment. In thisembodiment, the vehicle 100 includes an engine system 102 configured toprovide power for the vehicle. The engine system 102 can include theventilation system and diagnostics described herein. Although a truckhas been illustrated, the vehicle can be any type that can use an enginesystem 102 with a ventilation system. Furthermore, in an embodiment, theengine system 102 can, but need not directly provide locomotive powerfor the vehicle 100. For example, the engine system 102 can beconfigurable to drive an electric motor and/or generator.

FIG. 2 is a diagram of an engine system with a ventilation systemaccording to an embodiment. In this embodiment, the engine system 200includes an engine 202 with a valve cover 206. Air is supplied from theair intake 212 to the engine 202 through a compressor 216. Thecompressor 216 is configured to compress air from the air intake 212.

As illustrated in this embodiment, the ventilation system 208 is coupledbetween the valve cover 206 and the air intake 212. However, theventilation system 208 can be coupled to a chamber of the engine 202 ina variety of ways. For example, the ventilation system can be coupled tothe crankcase 204. Accordingly, the ventilation system 208 can be influid communication with the crankcase 204. Although a crankcase 204 hasbeen used as an example, any chamber of the engine 202 into whichcombustion gases can leak can be ventilated with the ventilation system208 or other ventilation systems described herein.

In an embodiment, the ventilation system 208 is coupled to the airintake 212. In particular, the ventilation system 208 can be coupled toanywhere on an upstream side of the compressor 216 where an amount ofvacuum can be generated. For example, the ventilation system 208 can becoupled to an inlet of the compressor 216, between the compressor 216and an air filter (not illustrated), or the like. Although a compressor216 has been illustrated, in another embodiment, the ventilation system208 can be coupled to a throttle body, upstream of the throttle body, orthe like in an normally aspirated engine. Regardless, the ventilationsystem 208 can be in fluid communication with the air intake 212.

The ventilation system 208 includes a pressure sensor 210. The pressuresensor 210 is disposed in fluid communication with the air intake 212and disposed between the air intake 212 and the crankcase 204. Thepressure sensor 210 can be configured to measure an amount of vacuum.Although the pressure sensor 210 is illustrated as inline with theventilation system 208, the pressure sensor 210 can be offset from theventilation system 208, connected with a pitot tube, or the like, yetstill in fluid communication with the ventilation system 208.

In an embodiment, when the compressor 216 is active, an amount of vacuumis produced in the air intake 212. The pressure sensor 210 can becoupled to the air intake 212 through hoses, pipes, fittings, or thelike of the ventilation system 208. If the connection is intact, thevacuum is communicated to the pressure sensor 210. However, if there isa breach in the ventilation system between the pressure sensor 210 andthe air intake 212, the vacuum will not be communicated, and thepressure sensor 210 can sense a higher pressure, including an ambientpressure. This difference in pressure can be used to determine a faultin the ventilation system 208.

For example, a processor 218 can be coupled to the pressure sensor 210.The processor 218 can be configured to determine a breach in aventilation system 208 in response to the pressure sensor 210. Theprocessor 218 can be any variety of processor. For example, theprocessor 218 can include a general purpose processor, amicrocontroller, an application specific integrated circuit, aprogrammable logic device, a combination of such devices, or the like.

In this embodiment, the processor 218 is part of an on-board diagnostic(OBD) system 220. The OBD system 220 can include inputs from othersensors such as a throttle position sensor 224, an engine speed sensor226, a crankshaft position sensor 228, a boost pressure sensor 230, orthe like. As will be described in further detail below, the processor218 can be configured to use signals from such sensors in determining abreach in the ventilation system 208.

In an embodiment, the processor 218 can be configured to filter a signalfrom the pressure sensor 210. In an embodiment, a low pass filter,averaging filter, or the like can be used. However, in anotherembodiment, non-time based filtering can be used. For example, thepressure sensor 210 signal can be gated by engine load, acceleration,whether the engine 202 is operating in a steady state, or the like. Thefiltered pressure signal can be used to determine a breach in theventilation system 208.

An embodiment can include means for measuring an amount of vacuum withina ventilation system 208 between a chamber of an engine and an airintake. An example of such means includes the pressure sensor 210, otherpressure sensors as described herein, and other similar structures.

An embodiment can include means for determining a breach in theventilation system 208 in response to the amount of vacuum. Theprocessor 218 and other similar circuitry can be configured to determinethe breach in response to the pressure sensor 210.

Although a compressor 216 has been illustrated as directly coupled tothe engine 202, other associated components can be part of the enginesystem 200. For example, a turbine coupled to the exhaust to drive thecompressor 216, a throttle, intercooler, or the like can be part of theengine system 200 but were omitted for ease of illustration.

An amount of vacuum has been used to describe a condition sensed by thepressure sensor 210. The sensed condition can, but need not be a vacuum.For example, the sensed condition can be an absolute pressure, arelative pressure, or the like. In an embodiment, any sensed conditionthat can indicate whether a pressure in the air intake 212 issubstantially communicated to a location within the ventilation system208 can be used to determine a breach in at least the section of theventilation system 208 between the location and the air intake 212.

FIG. 3 is a diagram of a ventilation system according to an embodiment.In this embodiment, the ventilation system 308 includes an oil separator312 and a pressure sensor 310. As part of the ventilation system 308,the oil separator 312 can be disposed between the crankcase 204 and theair intake 212.

The oil separator 312 can be any variety of devices. For example, theoil separator 312 can be a filter, baffles, screens, or the like.Although illustrated as separate from the engine 202, the oil separator312 can be part of the engine 202, such as being integrated with thevalve cover 206 or other structure of the engine 202. However, even whenso integrated, the oil separator 312 can still be disposed between thecrankcase 204 and the air intake 212.

In an embodiment, the pressure sensor 310 is disposed between the oilseparator 312 and the air intake 212. Accordingly, a breach between theoil separator 312 and the air intake 212 in the ventilation system 308can be detected using the pressure sensor 310.

In an embodiment, the oil separator 312 and/or other components betweenthe pressure sensor 310 and the crankcase 204 can be secured with bolts,nuts, or the like such that in operation the attachment is unlikely tobecome undone. In an embodiment, the oil separator 312 and/or othercomponents can be rigidly coupled to the engine 202.

However, the connections of the ventilation system 308 furtherdownstream from the oil separator 312 may not be as securely fastened.In operation, such connections can become loose, leak, rupture, orotherwise vent combustion gasses. According, the pressure sensor 310 canbe used to diagnose breaches downstream from such substantially securelyor rigidly coupled components.

FIG. 4 is a diagram of a connection between a pressure sensor and an airintake according to an embodiment. In this embodiment, the ventilationsystem 400 can include a housing 402 with a fitting 406. The housing 402can be the oil separator 312, valve cover 206, or the like describedherein, or other component upstream towards the crankcase 204. Thefitting 406 can include a barb, nipple, or other structure for attachinga hose, pipe, or the like.

The pressure sensor 408 can be disposed in the housing 402. In thisembodiment, the pressure sensor 408 is disposed in the fitting 406;however, the pressure sensor could be in line with the housing 402,fitting 406, or the like.

The ventilation system 400 also includes a second housing 404 includinga fitting 410. For example, the second housing 404 can be a housing ofan inlet of a compressor, an air intake pipe, or the like. The fitting410 can be similar to the fitting 406; however, in another embodiment,the fitting 410 need not be the same.

A hose 412 can be coupled to the fittings 406 and 410. The connectioncan be formed using hose clamps 414 and 416, barbs of the fittings, acombination of such or similar techniques, or the like. As a result, thehose 412 and connections to the hose 412 can substantially seal apassage from the pressure sensor 408 to the housing 404. However, assuch connections can be used where the attached components can moverelative to one another, such connections can fail. Furthermore, suchconnections may be disconnected during maintenance, repair, or the liketo access other parts and may be inadvertently left disconnected.Accordingly, an amount of vacuum from the second housing 404 would notpropagate to the pressure sensor 408 and a fault can be detected. Inother words, in an embodiment, the pressure sensor 408 can be disposedto sense a pressure in the ventilation system 400 at a location towardsthe crankcase 204 where, between the pressure sensor 408 and thecrankcase 204, the connections, seals, or the like of the ventilationsystem 400 are more rigid and/or are less likely to fail in operationthan those downstream from the pressure sensor 408.

Although one hose 412 has been illustrated, connections between thepressure sensor 408 and the housing 404 can include multipleconnections, multiple types of conduits, or the like. For example, ahose can couple the housing 402 to a rigid pipe, which is in turncoupled by another hose to the housing 404.

Referring back to FIG. 3, an embodiment can include means for separatingoil from a gas in the ventilation system 308. The means for separatingcan include a separate oil separator 312, structures within the valvecover 206, or other similar structures to separate oil from combustiongasses in the crankcase 204.

FIG. 5 is a graph of pressure versus load according to an embodiment.Graph 500 illustrates an example of pressure 502 versus engine load 504.Axis 502 illustrates absolute pressure. Thus, a decreasing value is anincreasing amount of vacuum. Curve 510 illustrates an example of anamount of vacuum sensed by a pressure sensor described above when thereis not a breach.

Line 506 illustrates an ambient pressure. Line 508 illustrates athreshold pressure or amount of vacuum. Line 512 illustrates a thresholdengine load. In an embodiment, this threshold can be an amount ofvacuum, a pressure that is less than ambient, or the like.

Referring to FIGS. 2 and 5, in an embodiment, if the amount of vacuum isgreater than or equal to the threshold 508, the processor 218 can beconfigured to determine that the ventilation system 208 has not failed.For example, curve 510 can represent an output of the pressure sensor208. In some conditions, the amount of vacuum indicated by curve 510 isgreater than the threshold 508. That is, a vacuum from the air intake212 is communicated to the pressure sensor 210, indicating that there isnot a breach.

In contrast, curve 514 represents a condition where there is a breach inthe ventilation system 208. Accordingly, a vacuum in the air intake 212is not substantially communicated to the pressure sensor 210. As thesensed amount of vacuum is less than the threshold 508, a determinationcan be made that there is a breach in the ventilation system 208.

In an embodiment, during some operating conditions, the sensed pressurecan enter a region were a fault would otherwise be indicated. Forexample, under lower engine load conditions, an amount of vacuum at theair intake 212 may be less than the threshold 508. Thus, even if thevacuum is perfectly communicated to the pressure sensor 210, the amountof the vacuum would be less than the threshold 508, potentiallyindicating a fault.

Accordingly, the engine load can be used in the determination of abreach. For example, an engine load threshold 512 can be used wherepressure readings obtained when the load is less than the threshold 512are disregarded. Although one threshold has been illustrated, any numberof thresholds of the engine load can be used depending on an expectedvacuum at the air intake 212.

The load of the engine 202 can be determined in a variety of ways. Forexample, a throttle position, an engine speed, a manifold pressure, aboost pressure, a combination of such conditions, or the like can beused to indicate the engine load. Although engine load has been used asthe axis 504 and used as an example, any engine parameter that, whenvaried, has a range associated with an intake vacuum greater than athreshold can be used to diagnose the ventilation system 208. That is,in an embodiment, the parameter can be used to gate the pressure signalso that the pressure is not used when the pressure signal may indicate afalse positive and/or false negative.

FIG. 6 is a diagram of a ventilation system according to anotherembodiment. In this embodiment, the ventilation system 608 includes avalve 612. For example, the valve 612 can be a crankcase depressionregulator valve configured to limit an amount of vacuum applied to thecrankcase 204.

The pressure sensor 610 can be disposed between the valve 612 and theair intake 212. Accordingly, an operation of the valve can have areduced, if not eliminated effect on the propagation of the vacuum fromthe air intake 212 to the pressure sensor 610.

Although a valve 612 has been used as an example, the pressure sensor610 can be disposed on the air intake 212 side of any structure that canlimit the propagation of pressure changes to the pressure sensor 610.For example, the pressure sensor 610 can be disposed between the airintake 212 and an orifice, a restriction, or the like.

An embodiment can include means for limiting a vacuum of the chamber. Asdescribed above, a valve, orifice, restriction, or the like can limitthe vacuum of the crankcase 204. The means for limiting the vacuum caninclude such devices and/or structures, or the like.

FIG. 7 is a flowchart of a diagnostic technique according to anembodiment. In an embodiment, in 700 an amount of vacuum within aventilation system between a chamber of an engine and an air intake ismeasured. As described above, the amount of vacuum can be measured withone or more pressure sensors disposed in fluid communication with theventilation system. In 702, a breach in the ventilation system can bedetermined in response to the amount of vacuum. As described above, ifthe amount of vacuum is below a threshold, the lack of vacuum canindicate a breach. As described above, part of measuring the amount ofvacuum can include filtering the measured amount.

FIG. 8 is a flowchart of a diagnostic technique according to anotherembodiment. In this embodiment, in 804, oil is separated from a gas inthe ventilation system. As described above, the separation can beperformed by an oil separator, filter, baffles, or the like. After theseparation in 804, the amount of vacuum within the ventilation systemcan be measured in 800 and a determination of a breach made in 802.

FIG. 9 is a flowchart of a diagnostic technique according to anotherembodiment. In this embodiment, the amount of vacuum is measured in 900.The amount of vacuum is compared with a threshold in 902. Based on thecomparison, a determination can be made whether there is a failure in904 or whether the system has passed in 906.

For example, if the amount of vacuum is less than the threshold, adetermination of a failure of the ventilation system can be made in 904.If the amount of vacuum is greater than or equal to the threshold, adetermination cam be made in 906 that there is not a failure of theventilation system .

As described above, the vacuum propagated from the air intake to achamber of the engine can be limited. The measuring of the amount of thevacuum can be performed in a manner substantially independent of thelimiting of the vacuum of the chamber. That is, the amount of vacuum canbe measured in 900 at a location towards the air intake from a limitingstructure. Alternatively, the amount of vacuum can be measured in 900during a period when the vacuum is not limited. Thus, the measurementcan remain substantially independent of the limiting of the vacuum.

FIG. 10 is a flowchart of a diagnostic technique according to anotherembodiment. In this embodiment, in 1000, an amount of vacuum ismeasured. In 1002, an amount of vacuum expected to be produced by theengine is compared against a threshold.

Although an expected amount of vacuum is used explicitly, the comparisoncan occur through a proxy for the expected vacuum. As described above,various engine parameters can act as a proxy for an expected vacuum. Thecomparison of one or more of these parameters with one or morethresholds can be the comparison in 1002.

The amount of vacuum is compared in 1002 to see if it is greater than orequal to a threshold. In an embodiment, the threshold can be an amountof vacuum greater than a threshold used to determine a breach in theventilation system. If a sufficient vacuum is not expected, then theprocess can continue in 1006 without making a determination.Alternatively, if there is a sufficient expected amount of vacuum, adetermination of whether there is a failure can be made in 1004.

Although the terms greater than, less than, and equal have been usedwith respect to an amount of vacuum, any such comparison can beappropriately performed when pressure is measured in other ways. Forexample, if pressure is measured as an absolute pressure, for an amountof vacuum that is greater than or equal to a threshold, the absolutepressure would be less than or equal to the threshold.

Although particular sequences of various operations have been given,unless explicitly stated, such operations can be performed in variousorders, continuously or discretely, serially or in parallel, or thelike.

Although a breach has been used as an example of a failure, not allfailures are breaches and not all breaches are failures. For example, aclogged ventilation system can result in the vacuum of the air intakenot propagating to the pressure sensor. The ventilation system would notbe breached, yet it is not operating correctly and may vent combustiongasses if pressure in the crankcase builds beyond a limit.

In another example, a breach can be present in the ventilation system;however, a sufficient vacuum prevents escape of combustion gasses,and/or the released combustion gasses are relatively insignificant. Insuch circumstances, a breach may not be interpreted as a failure.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain exemplary embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinventions are desired to be protected. It should be understood thatwhile the use of words such as preferable, preferably, preferred or morepreferred utilized in the description above indicate that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, the scope being defined by the claims that follow. Inreading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

What is claimed is:
 1. A system, comprising: an engine including achamber; an air intake coupled to the engine; a pressure sensor disposedin fluid communication with the air intake and disposed between the airintake and the chamber; and a processor configured to determine a breachin a ventilation system of the chamber in response to the pressuresensor.
 2. The system of claim 1, wherein: the air intake comprises aninlet to a compressor; and the pressure sensor is disposed between theinlet and the chamber.
 3. The system of claim 1, wherein the processoris configured to receive a signal from the pressure sensor and filterthe signal.
 4. The system of claim 1, further comprising: an oilseparator disposed between the chamber and the air intake; wherein thepressure sensor is disposed between the oil separator and the airintake.
 5. The system of claim 4, wherein the oil separator is a filter.6. The system of claim 1, wherein at least one fitting substantiallyseals a passage between the pressure sensor and the air intake.
 7. Thesystem of claim 1, wherein the processor is configured to determine ifan amount of vacuum is greater than or equal to a threshold in responseto the pressure sensor.
 8. The system of claim 7, wherein the thresholdis a pressure less than an ambient air pressure.
 9. The system of claim1, wherein the processor is configured to determine the breach in theventilation system of the chamber when the engine is expected to producean amount of vacuum at the air intake greater than or equal to athreshold.
 10. The system of claim 1, wherein the processor isconfigured to determine the breach in the ventilation system of thechamber in response to a load of the engine.
 11. The system of claim 1,further comprising: a valve disposed between the chamber and the airintake; wherein the pressure sensor is disposed between the valve andthe air intake.
 12. The system of claim 11, wherein the valve is acrankcase depression regulator valve.
 13. A vehicle, comprising: anengine configured to provide power for the vehicle, the engine includinga chamber; a compressor configured to compress air for the engine, thecompressor including an air intake; a ventilation system disposed influid communication between the chamber and the air intake; a pressuresensor disposed in fluid communication with the ventilation system andconfigured to sense a pressure of the ventilation system; and anon-board diagnostic system coupled to the pressure sensor and configuredto determine a breach in the ventilation system in response to thepressure.
 14. The vehicle of claim 13, wherein the on-board diagnosticsystem is configured to receive a signal from the pressure sensor andfilter the signal.
 15. The vehicle of claim 13, further comprising: anoil separator disposed in the ventilation system; wherein the pressuresensor is disposed between the oil separator and the air intake.
 16. Thevehicle of claim 13, wherein at least one fitting substantially sealsthe ventilation system between the pressure sensor and the air intake.17. The vehicle of claim 13, wherein the on-board diagnostic system isconfigured to determine if an amount of vacuum is greater than or equalto a threshold in response to the pressure sensor.
 18. The vehicle ofclaim 13, wherein the on-board diagnostic system is configured todetermine the breach in the ventilation system when the engine isexpected to produce an amount of vacuum at the air intake greater thanor equal to a threshold.
 19. The vehicle of claim 13, furthercomprising: a valve disposed in the ventilation system; wherein thepressure sensor is disposed between the valve and the air intake.
 20. Amethod, comprising: measuring an amount of vacuum within a ventilationsystem between a chamber of an engine and an air intake; and determininga breach in the ventilation system in response to the amount of vacuum.21. The method of claim 20, further comprising: filtering the measuredamount of vacuum; and determining the breach in the ventilation systemin response to the filtered measured amount of vacuum.
 22. The method ofclaim 20, further comprising: separating oil from a gas in theventilation system; and measuring the amount of vacuum within theventilation system after separating the oil from the gas.
 23. The methodof claim 20, further comprising: comparing the measured amount of vacuumto a threshold; and determining the breach in the ventilation system inresponse to the comparison.
 24. The method of claim 20, furthercomprising: determining if an amount of vacuum expected to be producedby the engine at the air intake is greater than or equal to a threshold;and determining the breach in the ventilation system in response to theamount of vacuum expected to be produced by the engine.
 25. The methodof claim 20, further comprising: limiting a vacuum of the chamber; andmeasuring the amount of vacuum within a ventilation system that issubstantially independent of the limiting of the vacuum of the chamber.26. A system, comprising: means for measuring an amount of vacuum withina ventilation system between a chamber of an engine and an air intake;and means for determining a breach in the ventilation system in responseto the amount of vacuum.
 27. The system of claim 26, further comprising:means for separating oil from a gas in the ventilation system; whereinthe means for measuring the amount of vacuum is disposed between themeans for separating and the air intake.
 28. The system of claim 26,further comprising means for determining if the amount of vacuum isgreater than or equal to a threshold.
 29. The system of claim 26,wherein the means for determining the breach in the ventilation systemis configured to determine the breach in the ventilation system inresponse to an amount of vacuum expected to be produced by the engine.30. The system of claim 26, further comprising: means for limiting avacuum of the chamber; wherein the means for determining the breach inthe ventilation system is disposed between the means for limiting avacuum of the chamber and the air intake.